ASTRO 2015
Novel approaches to treating oligometastases
Dr Morten Høyer - Aarhus University Hospital, Aarhus, Denmark
For almost twenty years people have treated patients with limited numbers of metastases with radiation therapy, stereotactic radiotherapy or SBRT.
So far there has been very limited evidence for these treatments.
Nowadays there are an increasing number of phase I and II studies and also some retrospective cohort studies in patients being treated with SBRT so that we know some more about the outcome of this treatment, local control and morbidity and prognostic factors.
Can you tell us about SBRT and what is unique about this form of radiation therapy?
The unique thing is that you’re treating very precisely a small volume, which is the tumour, with a very small margin with a few fractions.
What will you cover in your talk on survival after SBRT of colorectal carcinoma oligometastases?
What I will talk about is the experience that we have had so far with the treatment of patients in our institution. We have treated over fifteen years more than 200 patients and these are the results I am going to talk about.
Are the patients treated with radiotherapy or surgery first?
We have actually found that approximately 20% of the patients are alive at five years which is quite good considering that these patients were judged as unfit for surgery, unfit for radiofrequency ablation at the time they were treated.
So could you be using this form of radiation earlier in the disease process?
No, actually 40% of the patients had a prior local treatment for metastasis and were then referred for treatment of subsequent metastases. So we treated patients who had quite some extent of their disease.
Are you aware of any phase III trials ongoing or are you performing any?
It could be possible to treat more patients than we do today, for sure, but first of all we have to prove that stereotactic body radiation therapy is an efficient treatment and for that reason we have to go into a phase III trial now. I think the time has come where we really need to do randomised trials to prove the efficacy of this treatment.
Are you aware of any phase III trials ongoing or are you performing any?
There are, actually, trials ongoing in breast and colorectal cancer metastasis treatment. I’m sure that there will be some years to go before that will happen.
What could be some of the downsides of using SBRT?
There are very few downsides in this treatment, actually. The side effects are really few, especially if you are trained in SBRT. We know that experience is important if you’re going for the lowest possible risk of side effects.
The session focuses on colorectal and liver metastases but what about the use of SBRT for brain metastases?
The brain has been treated for a very long time and we have quite some experience there. We even have randomised trials to show that it works in brain, especially for patients with a single brain metastasis. We know that survival is improved by stereotactic radiotherapy in brain.
When you treat patients are you treating metastases in one organ or can you target metastatic lesions in multiple organs?
It is actually possible to treat patients with metastases in more than one organ but we also know that it’s a negative prognostic factor if the patient has more than one organ involved.
Is there anything else about your talk you would like to highlight?
First of all, we now have some very important information about the long-term survival of some patients treated with SBRT. Secondly, that we do know about prognostic factors so that we can actually choose the right patients for this treatment. I think that’s the important thing that we know so far.
Could you tell us what the prognostic factors are?
The prognostic factor is actually the patient’s performance status, it’s a number and it’s also the size of the largest metastasis. We did also find, but only in a [?? 5:01] analysis, that patients who also received systemic therapy in combination with the stereotactic radiotherapy did better in terms of survival.
What was the systematic therapy used?
That was chemotherapy and in my view this actually is quite a strong indication that we should combine with chemotherapy instead of using, or try to replace chemotherapy with a local therapy such as SBRT.
What about using SBRT without immunotherapy?
That is a very, very interesting area and I think that a combination of immune stimulation with one of the new drugs could be a very important agent combined to SBRT.
